Methods of installing an elongated, flexible, electric heater into a material storage tank, and heater construction for the same

ABSTRACT

Methods of installing an elongated, flexible, electric heater into a material storage tank comprising attaching flexible cables to opposite ends of the heater while the same is disposed exteriorly of the tank, and utilizing such cables to guide the heater to a selected position within the tank. The invention also includes novel heater construction which is particularly useful in carrying out the methods.

United States Patent 1191 Caroleo Feb. 25, 1975 54] METHODS OFINSTALLING AN 1,676,510 7/1928 Welcomek 219/523 x T 1 1,723,743 8/1929Mason 219/523 g j gggfifig kgfi i 22 12 2,888,546 5/1959 Kinney 219/318x 3,286,079 11/1966 Hynes et a1. 219/523 X TANK, AND HEATER CONSTRUCTIONF OR 3,673,385 6/1972 Drugmand 219/523 x THE SAME Inventor: Steven J.Caroleo, Coraopolis, Pa.

Assignee: Emerson Electric Co., St. Louis, Mo.

Mar. 16, 1973 Appl. No.: 341,968

Related US. Application Data Division of Ser. No. 206,666, Dec. 10,1971, Pat. No. 3,745,640.

US Cl 219/318, 29/433, 219/335,

219/336, 219/523 Int. Cl. HOSb 1/00 Field of Search 219/316, 318, 335,336, 219/306, 523, 535-537; 126/367; 29/433, 469

Primary ExaminerC. L. Albritton Attorney, Agent, or Firm-MichaelWilliams [57] ABSTRACT Methods of installing an elongated, flexible,electric heater into a material storage tank comprising attachingflexible cables to opposite ends of the heater while the same isdisposed exteriorly of the tank, and utilizing such cables to guide theheater to a selected position within the tank. The invention alsoincludes novel heater construction which is particularly useful incarrying out the methods.

1 Claim, 18 Drawing Figures PATENTEU FEB 2 5 ms I snmzqm This is adivision, of application Ser. No. 206,666, filed Dec. 10, 1971 now US.Pat. No. 3,745,640.

BACKGROUND AND SUMMARY Many substances are stored in large, steel,concrete or fibrous tanks and require heat at all time, or periodically,to maintain such substance in fluid condition. Such tanks may beunderground, above-ground, process vessels, or tanks enclosed inconcrete, all having some sort of opening, such as a manhole entry.

Tanks containing fuel oil are included in this category, the coil havingmany uses, as for providing fuel for burners to provide heat fordwellings, or steam for generation of power. With the growing concernabout air pollution, usershave turned to a viscous fuel oil, having alow sulfur content, since it was found that combustion of this oilproduced very little aircontaminating matter. However, a seriousdisadvantage arose because of the fact that this oil was required to beheated, otherwise, itwould congeal to a mass which could not be removedfrom the tank by the ordinary pumping equipment, or by gravity flow.

Tank heaters for heating high viscosity materials, such as asphalt andheavy oils and other materials, are known in the art, and examples areillustrated in Reissue patent Re. 954, issued to Alfred Karcher on Dec.27, 1938, and US. Pat. No. 2,888,546, issued to Theodore S. Kenney onMay 26, 1959.

Flexibility of the heater, at least in the longitudinal direction, isrequired in order to install the same through the manhole opening of thetank. These heaters are now made in lengths of from 12 feet to over 20feet and it will be appreciated that their flexibility renders them limpand difficult to handle. This is so particularly where a heater isinstalled in a tank which already contains oil, since it is difficult tovisually observe whether or not the heater has been properly moved to adesired position. Further, even if all oil has been pumped or drainedfrom the tank, many states have regulations which forbid a person fromentering a tank that contains oil, or has contained oil, because of thehealth hazards involved.

My invention makes itpossible to dispose a flexible electric heaterwithin a tank either containing oil, or free of oil, by means controlledfrom the exterior of the tank, and thus overcomes the various hazardsand difficulties above mentioned.

DESCRIPTION OF THE DRAWINGS In the drawing accompanying this descriptionand forming a part of this specification, there are shown, for purposesof illustration, several embodiments which my invention may assume, andin these drawings:

FIG. 1 is a perspective view of a representative heater, showing aworkman holding up one end to demonstrate the flexibility and length ofthe heater,

FIG. 2 is an end view of the heater shown in FIG. 1,

FIG. 2 A is a section corresponding to the line 2-2 of FIG. 2,

FIG. 3 is an end view of a similar heater, but illustrating a singletube heater,

FIGS. 4 through 8 are schematic views illustrating steps in the methodof installing a flexible heater into a fluid storage tank,

FIG. 9 is a schematic view illustrating another method of installing theheater,

FIGS. 10 through 12 are schematic views illustrating steps in stillanother method of installing the heater into the tank,

FIGS. 13 and 14 are schematic views illustrating 5 steps installing aheater in a vertically disposed tank, and

FIGS. 15 through 17 are schematic views illustrating steps in installinga heater in a vertically disposed tank wherein the manhole opening is atthe side of the tank.

DESCRIPTION OF THE PREFERRED EMBODIMENT The heater shown in FIG. 1comprises a pair of metallic sheaths 20, 21 formed of flexible tubing,such as corrugated metal tubing. Within each sheath is an elongatedresistance wire which is insulated from the sheath but is permitted toflex therewith. A form of resistance wire and insulator means which maybe utilized is shown in the aforementioned Kinney patent.

Each sheath is closed at the ends 22, and the opposite ends 23 are alsoclosed except for passage of flexible power conductors 24 which extendto a cover 25. The cover 25 is adapted to be bolted to the tank to closethe manhole opening therein, and conductor means (not shown) are adaptedto connect to a control box (also not shown) for controlling flow ofelectrical energy to the resistor wires in the sheaths 20, 21. Suitablecontrol means (not shown) may be used to regulate energization of theresistor wires, dependent upon the temperature of the fluid in the tankand upon the sheath temperature of the heaters.

Supports 26 are connected to the sheaths 20, 21 at places spacedlongitudinally thereof, to hold the heater spaced from the bottom of thetank and out of any sludge that might collect at the tank bottom. In thecase where the heater is formed of two sheaths, as seen in FIGS. 1 and2, the supports 26 also hold these sheaths in fixed laterally spacedrelation. Each support, as best seen in FIG. 2, comprises a U-shapedmetal step 27 and a cross-bar 28 bolted to respective legs of the strap.Each strap has pockets to partially embrace a respective sheath, thepockets in part being formed by a downwardly curved central portion 29.A bolt 30 is passed through aligned opening in the central portion 29and the cross-bar 28 and a nut 31 on the bolt provides a pulling forceso that the pockets of the straps tightly embrace respective sheaths tohold them firmly spaced. A metal foot 32 spans the ends of the legs ofthe strap 27 and is affixed thereto in any suitable manner, such as bywelding 33. It will be noted that the foot is of considerable thicknessand this is desirable to provide weight, and to lower the center ofgravity of the heater. Thus, as the heater is installed in the tank, theweight of the feet of the plurality of supports 26 causes the heater togravitate to the bottom of the tank, even in liquids of high density orviscosity. Also, because the weighted feet 32 provide a low center ofgravity, the heater will gravitate to the tank bottom with the feetlowermost. As best seen in FIG. 2 A, each foot is bevelled, as seen at32.] so that it may glide over obstructions, such as welding ridges, onthe lowermost wall of the tank.

Flexible cables 35, 36 are attached to the opposite ends of the heater,as seen in FIG. 1, and FIG. 2 shows one method of attaching the cables.Only the cable 36 is seen in FIG. 2 but it will be appreciated that thecable 35 may be similarly attached. It has been found that if the cable36 is looped around the bolt 30, the connection is suitable forinstallation purposes without imposing detrimental stresses on theheater construction.

The heater may be formed with only a single sheath 37, as seenin FIG. 3,in which case each support 26a comprises a U-shaped, metal strap 27ahaving a single pocket for partially encircling the sheath, and acrossbar 28a for confining the sheath. A weight foot 320 is secured tothe ends of the strap legs, for the same purpose as the foot 32. FIGS. 2and 3 show double and single sheaths, respectively, but three or moresheaths may be utilized, depending upon heating requirements. Since nobolt (like bolt 30) is required in FIG. 3, the cable 36 may be anchoredto an eye welded to the end of the sheath.

1 Since the sheaths 20, 21 (or 37) are very flexible, it will beappreciated that an elongated flexible heater is extremely difficult tohandle, particularly during the time it is being installed into thetank. v

FIGS. 4 through 8 show steps in a preferred method of installing anelongated flexible heater, of the types shown in FIGS. '1 and 3, into atank. The tank T in this case is underground, with its longitudinal axishorizontal and with a manhole opening 40 and a vent or fill pipe 41 inthe uppermost side wall of the tank, these openings being spacedsubstantial distance.

As seen in FIG. 4 the heater H, which is representative of a single orplural type sheath, is aligned along the centerline of the tank with theend 22 spaced to one side of the manhole opening. If the cables 35, 36have not been previously connected to the heater, they may be connectedat this time. Also, a safety cable (not shown) may be tied to theflexible power conductors 24 to hold them from being pulled into thetank too soon, since such conductors are preferably not connected to thecover 25 at the time the heater is installed into the tank. It will benoted that the feet 32 rest against the upper surface of the ground inFIG. 4 to provide firm support therefore during all operationspreparatory for installation. The cable 36 is disposed through themanhole opening 40, through the tank T and through and outwardly of thepipe 41. This may be accomplished by snaking a wire through the pipe 41,through the tank T and the manhole opening 40, and attaching it to .thefree end of the cable 36, and then pulling the wire in the reversedirection to pull the cable 36 to the position shown in FIG. 4.

The heater H is then turned over so that the feet 32 are uppermost, asseen in FIG. 5, and a workman may insert the end 22 into the manholewhile others control pulling force on the cables 35, 36. The heater willflex longitudinally, as seen in FIG. 6 and, since the feet 32 aredisposed away from engagement with the defining surface of the manholeopening 40, the heater will smoothly slide over such surface.

A pulling force applied to cable 36 will cause the heater end 20 to bedrawn toward the left end of the tank, while a pulling force on thecable 35 (less than applied to cable 36) will guide the heater end 23through the manhole opening 40, as seen in FIG. 7. It will be noted thatthe heater has been righted in this operation so that the feet 32 arelowermost. After the heater is fully disposed within the tank, thepulling forces on the cables 35, 36 may be gradually slackened so thatthe weight of the feet 32 will cause the heater to gravitate to thebottom of the tank as seen in FIG. 8.

Before the manhole cover 25 is bolted in place. the conductors 24 areproperly connected to it and the cables 35, 36 are secured to a suitableconnection on the underside of the cover so as to be accessible for usein the event the heater H is to be withdrawn from the tank T forreplacement, or repair and return. As seen in FIG. 8, the low profile ofthe heater provides for maximum use of tank volume, and permits heat tobe maintained in the oil even at low levels thereof. Further, throughuse of my invention, the heater may be installed in presently used tankswith no tank modifications or cleaning required.

DISCLOSURE OF OTHER EMBODIMENTS FIG. 9 shows a method of installing theheater H into a tank T which has no vent or fill pipe. The cables 35, 36as before, are attached to the opposite ends of the heater. In thiscase, the end 22 of the heater is inserted into the tank and is guidedbypulling forces on the cables, both of which in this case extendthrough the manhole opening. It will be noted that the cable maybe usedto maintain the feet 32 away from contact with the defining wall of themanhole opening.

FIGS. 10 through 12 illustrate steps in installing a heater H within atank T along the lines of the modification shown in FIG. 9,.except thatthe tank in this case is provided with a vent or fill, pipe 41. In FIG.10, the heater is shown as disposed to the right of the manhole openingwith its feet 32 resting on the ground support. The cable 36 has beendrawn through the pipe 41 and the forward end 22 of the heater may belifted by a workmanand inserted into the manhole opening. As seen inFIG. 11 the cable 35 may be usedto keep the feet 32 clear of thedefining surface of the manhole opening while a pulling force is appliedto the cable 36. When the heater is entirely within the tank T, it ispermitted to gravitate to the bottom wall thereof, and is guided toselected longitudinal position by pulling force applied to the cables.In case the heater is extremely long, or extremely flexible, a pluralityof cables may be attached at spaced supports 26 along its length, asshown by the dotted lines referenced 35a in FIG. 10.

FIGS. 13 and 14 illustrate steps in the method of installing a heater Hwithin a tank Ta which has its longitudinal axis vertical and has amanhole opening 40a and a vent of filler pipe 41a in its top end wall.As before, the cable 36 is connected to the end 20 of the heater anddrawn through the pipe 41a, and the cable 35 is connected to the end 23of the heater and is utilized to hold the feet 32 clear of the manholeopening. After the heater is fully disposed in the tank Ta, it ispermitted to gravitate to the lower end thereof, pulling forces on thecables being controlled to dispose the heater in selected position onthe bottom of the tank.

FIGS. 15 through 17 illustrate the steps used in insetting a heater H ina vertically disposed tank Tb wherein the manhole opening.40b and ventor filler pipe 4111 are disposed in the side wall of the tank with themanhole opening uppermost. In this case the heater is inverted, so thatits feet 32 are uppermost, and the end 22 is inserted horizontally intothe manhole opening until a sufficient length of heater is within thetank to permit longitudinal bending thereof by a pulling force on cable36. The heater is righted within the tank so that the feet 32 arelowermost, and the heater is then permitted to gravitate to the tankbottom.

I claim:

1. An elongated electric heater adapted to be disposed within a largefluid storage tank throughan opening in an upper portion of the tank andwhen so disposed having no mechanical connection with said tank,comprising:

a plurality of elongated metal sheaths disposed in side-by-siderelation, each sheath being formed of flexible tubing, such ascorrugated metal tubing, so that said sheath may be freely bent throughits longitudinal length whereby it may be manipulated for insertionthrough said tank opening to the interior of said tank,

an elongated flexible electric heating element positioned lengthwisewithin each of said sheaths, said heating element being electricallyinsulated from its sheath but permitted to flex therewith,

a plurality of supports connected to said metal sheaths atlongitudinally spaced places, each support comprising a bracket portionconnected to said sheaths and a foot portion spaced from said sheaths,each foot portion being adapted to rest on an interior lower wallsurface of said tank to space said sheaths therefrom,

each bracket portion spanning said sheaths and providing pockets forreceiving respective sheaths for holding them in predetermined spacedrelation, a cross bar for each bracket portion, said cross bar spanningsaid sheaths for holding the same in said pockets, a bolt extendingbetween a bracket portion and cross bar of at least one of saidsupports, and a flexible cable having one end anchored to said bolt,

each foot portion being weighted and said foot portions combining to actas weights to overcome any floating action of said heater within fluidin said tank and to cause said heater to gravitate to and remain on saidlower interior wall surface of said tank.

1. An elongated electric heater adapted to be disposed within a largefluid storage tank through an opening in an upper portion of the tankand when so disposed having no mechanical connection with said tank,comprising: a plurality of elongated metal sheaths disposed inside-by-side relation, each sheath being formed of flexible tubing, suchas corrugated metal tubing, so that said sheath may be freely bentthrough its longitudinal length whereby it may be manipulated forinsertion through said tank opening to the interior of said tank, anelongated flexible electric heating element positioned lengthwise withineach of said sheaths, said heating element being electrically insulatedfrom its sheath but permitted to flex therewith, a plurality of supportsconnected to said metal sheaths at longitudinally spaced places, eachsupport comprising a bracket portion connected to said sheaths and afoot portion spaced from said sheaths, each foot portion being adaptedto rest on an interior lower wall suRface of said tank to space saidsheaths therefrom, each bracket portion spanning said sheaths andproviding pockets for receiving respective sheaths for holding them inpredetermined spaced relation, a cross bar for each bracket portion,said cross bar spanning said sheaths for holding the same in saidpockets, a bolt extending between a bracket portion and cross bar of atleast one of said supports, and a flexible cable having one end anchoredto said bolt, each foot portion being weighted and said foot portionscombining to act as weights to overcome any floating action of saidheater within fluid in said tank and to cause said heater to gravitateto and remain on said lower interior wall surface of said tank.